1. Field of the Invention
The present invention relates to a technology for displaying genetic information of biological tissues.
2. Description of the Related Art
Determination of the characteristi of the manner and at what time a gene is expressed in a specific tissue is important in terms of understanding the involvement of genes in biophenomena. In particular, a comparison of the transcription levels of two genes between “diseased tissue and normal tissue” and “diseased tissue and drug-administered tissue” is typically carried out, and is frequently used in the clinical and drug development settings.
Since the level of gene expression used as a reference in such comparisons varies considerably depending on the tissue and time, it cannot be determined precisely. Consequently, a characteristic gene is currently specified using the ratio of expression levels between two genes. For example, in the microarray method, which is frequently used to compare gene transcription levels, transcription levels are quantified by labeling mRNA (DNA transcription product) in the body with a fluorochrome dye, causing the dye to emit light, and then detecting the fluorescence intensity (arbitrary units) with a detector.
A system that handles genetic information has been disclosed in, for example, Japanese Patent Application Laid-open No. H11-342000. In this system, the expression levels of predetermined genes collected from two tissue samples are respectively defined as the horizontal or vertical axis, and the expression levels of the predetermined genes are visualized by a computer-assisted comparison of expression arranged at a site selected on the horizontal and vertical axes based on the expressed state in the two tissue samples.
Accompanying increasing activity in research on the interaction between genes and proteins, gene network diagrams are being disclosed on websites and researchers are using those diagrams. Analysis of expression using microarrays and gene chips will be an important key when verifying the interactions between genes in existing network diagrams and attempting to expand upon those diagrams (for example, see “Kyoto Encyclopedia of Genes and Genomes (KEGG)”, available online on 13 Jul. 2005, and “BioCarta” available online, on 13 Jul. 2005).
As indicated in Japanese Patent Application Laid-open No. H11-342000, although techniques have been proposed for scoring levels of gene expression by combining the expression levels (intensities) and expression level ratios of genes when administering a drug and not administering a drug for normal tissue and diseased tissue, respectively, since the score is not considered to be intuitive by researchers, it has a problem of being difficult to understand.
When network diagrams disclosed in KEGG and BioCarta are used, the scores for each of the large number of genes in the network diagram must be displayed on a limited screen. Thus, if the scores are comprehensively displayed in the blank areas of the network diagram, in addition to the scores being difficult to understand intuitively, the overall network diagram becomes illegible, resulting in a problem of considerable inconvenience for researchers.
Furthermore, when the expression levels of two genes are compared, for example, even if the expression levels of both genes increased by the same factor of 1.2, when the gene expression level (mRNA level) of a gene A has increased from 2000 to 2400, and the gene expression level (mRNA level) of a gene B has increased from 5 to 6, the increased gene expression levels differ by 400-fold between the gene A and the gene B. In this case, although the phenomenon of increased expression of the gene A is biologically significant, if displayed based on the increase in the gene expression of the gene B, it becomes difficult to observe the biologically significant gene expression of the gene A, thus resulting in a problem of being inconvenient for researchers.